arXiv subjects

Arash Azizi

Publications and source records attributed to Arash Azizi.

24 records · Page 2Linked to original sources

arXiv2025

Hodge Duals in Spherical Compactifications

We present a general formalism for computing the Hodge dual of differential forms in arbitrary dimensions subject to a spherical constraint. This problem arises naturally in Kaluza-Klein compactifications, where sphere reductions demand careful treatment of differential forms constrained to lie on embedded submanifolds. We derive an explicit expression for the Hodge dual of a $p$-form in the presence of such constraints and validate our general ansatz through illustrative examples in three dimensions, including both flat and diagonal metric backgrounds. The resulting framework offers a systematic and practical tool for handling constrained Hodge duals, with direct applications to consistent truncations in supergravity and string theory compactifications.

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arXiv2025

Time-Ordering in the Dyson-Unruh Problem: Accelerated Observers and Quantum Fields

We investigate the structure of time-ordered perturbative expansions in quantum field theory (QFT) in curved spacetime, focusing on the interaction between a scalar field and multiple Unruh-DeWitt detectors undergoing uniform acceleration. Assuming the existence of a timelike Killing vector field, which serves as a global time coordinate, we express each detector's proper time in terms of this global time and consistently implement time-ordering in the Dyson series. Using light-cone coordinates and detector worldlines, we construct all possible interaction terms for two detectors at first, second, and third orders in perturbation theory. Our formalism enables a systematic classification of contributions to the S-matrix, resolving ordering ambiguities that arise due to differing accelerations and causal structure.

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arXiv2023

Kappa vacua: Enhancing the Unruh temperature

We elaborate more on $κ$-mode, a mode that was found by a combination of Rindler modes in the right and left Rindler wedges with opposite sign norms. We find a relation between different kappa vacua, which is a generalization of the thermofield double state. However, a $κ$-vacuum can be written in terms of the Rindler vacuum as the thermofield double state, with a modified Unruh temperature of $T_κ=\frac{\hbar a}{2πc k_B}\,κ$. Consequently, when a uniformly accelerated observer with an acceleration $a$ is immersed in a $κ$-vacuum, they perceive a thermal bath. However, the temperature experienced by the observer is a modified Unruh temperature denoted as $T_κ$. Remarkably, the Unruh temperature can be enhanced by an arbitrary factor of $κ$.

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arXiv2023

Kappa vacua: Infinite number of new vacua in two-dimensional quantum field theory

We uncover an infinite number of vacua in two-dimensional quantum field theory, the Klein-Gordon field for simplicity, by conceiving a new mode that is classified by a real positive parameter $κ$. We show each mode has a distinct vacuum, say $κ$-vacuum. This new mode is a generalization of the Unruh-Minkowski mode. Moreover, the Minkowski and Rindler vacua are special cases of the $κ$-vacuum for $κ= 1$ and $κ\rightarrow \infty$, respectively.

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arXiv2018

On Pauli Reductions of Supergravities in Six and Five Dimensions

The dimensional reduction of a generic theory on a curved internal space such as a sphere does not admit a consistent truncation to a finite set of fields that includes the Yang-Mills gauge bosons of the isometry group. In rare cases, for example the $S^7$ reduction of eleven-dimensional supergravity, such a consistent "Pauli reduction" does exist. In this paper we study this existence question in two examples of $S^2$ reductions of supergravities. We do this by making use of a relation between certain $S^2$ reductions and group manifold $S^3=SU(2)$ reductions of a theory in one dimension higher. By this means we establish the non-existence of a consistent $S^2$ Pauli reduction of five-dimensional minimal supergravity. We also show that a previously-discovered consistent Pauli reduction of six-dimensional Salam-Sezgin supergravity can be elegantly understood via a group-manifold reduction from seven dimensions.

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arXiv2016

The Embedding of Gauged STU Supergravity in Eleven Dimensions

The consistency of the embedding of four-dimensional SO(8) gauged N=8 supergravity into eleven-dimensional supergravity, where the internal directions are compactified on a seven-sphere, was established by de Wit and Nicolai in the 1980s. The reduction ansatz for the eleven-dimensional metric, and for some of the components of the 4-form field strength, were found at that time, and recently the complete expression for the 4-form reduction has been obtained. The expressions are quite complicated, and in many practical applications it would be sufficient to know the ansatz for a subset of the four-dimensional fields. In this paper, we obtain explicit expressions for the embedding of the truncation of the full N=8 gauged theory to the N=2 gauged STU supergravity. This corresponds, in the bosonic sector, to a consistent truncation of the N=8 supergravity fields to those that are singlets under the U(1)^4 Cartan subalgebra of SO(8). This truncation to STU supergravity, which comprises N=2 supergravity coupled to three vector multiplets, suffices, for example, for lifting the general 8-charge asymptotically-AdS rotating black holes to eleven dimensions. We also give two distinct further truncations to N=2 supergravities coupled to single vector multiplets.

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